Fault-controlled regional magmatism and mineral deposition in central Cathaysia—Evidence from ambient noise tomography     

Cao  Lingmin  Yuan  Huaiyu  Zhao  Liang  Zhao  Minghui  Huang  Haibo  Hao  Tianyao  Qiu  Xuelin 《中国科学:地球科学(英文版)》2022,65(9):1715-1735

Science China Earth Sciences - Guangdong Province in the central Cathaysian Block has two world-class metallogenic belts, namely, the Nanling and Southeastern Coastal Metallogenic Belts (NLMB and...  相似文献   

Crust and Upper Mantle Electrical Resistivity Structure in the Panxi Region of the Eastern Tibetan Plateau and Its Significance   总被引：3，自引：0，他引：3  

ZHANG Gang  WANG Xuben  FANG Hui  GUO Ziming  ZHANG Zhaobin  LUO Wei  CAI Xuelin  LI Jun  LI Zhong  WU Xing 《《地质学报》英文版》2015,89(2):531-541

The Panxi region is located in the frontal zone of positive squeezing subduction and side squeezing shearing between the Indian plate and the Eurasian plate. The long-period magnetotelluric(LMT) and broadband magnetotelluric(MT) techniques are both used to study the deep electrical conductivity structure in this region; magnetic and gravity surveys are also performed along the profile. According to the 2-D resistivity model along the Yanyuan-Yongshan profile,a highconductivity layer(HCL) exists widely in the crust,and a high-resistivity block(HRB) exists widely in the upper mantle in general,as seen by the fact that a large HCL exists from the western Jinpingshan tectonic zone to the eastern Mabian tectonic zone in the crust,while the HRB found in the Panxi tectonic zone is of abnormally high resistivity in that background compared to both sides of Panxi tectonic zone. In addition,the gravity and magnetic field anomalies are of high value. Combined with geological data,the results indicate that there probably exists basic or ultrabasic rock with a large thickness in the lithosphere in the Panxi axial region,which indicates that fracture activity once occurred in the lithosphere. As a result,we can infer that the high-resistivity zone in the Panxi lithosphere is the eruption channel for Permian Emeishan basalt and the accumulation channel for basic and ultrabasic rock. The seismic sources along the profile are counted according to seismic record data. The results indicate that the most violent earthquake sources are located at the binding site of the HRB and the HCL,where the tectonic activity zone is generally acknowledged to be; however,the earthquakes occurring in the HCL are not so violent,which reflects the fact that the HCL is a plastic layer,and the fracture threshold of a plastic layer is low generally,making high stress difficult to accumulate but easy to release in the layer. As a result,a higher number of smaller earthquakes occurred in the HCL at Daliangshan tectonic zone,and violent earthquakes occurred at the binding site of high- and low-resistivity blocks at the Panxi tectonic zone.  相似文献   

论创建结构化知识教学——以地理学科为背景     

王学涛  喻学林 《地理教学》2021,(3):36-41

教学中知识是有结构的,学生是创建结构化知识的主体对象。创建学科结构化知识教学需走出"必备知识碎片化""非必备知识结构化""必备知识结构错误化""知识结构化教学设计粗放化"等偏向。以学为中心的学科概念教学是创建结构化知识教学的本质特征。创建学科结构化知识的结构化教学旨趣是遵循认知规律、学为中心、结构价值的流程。  相似文献   

中国大陆岩石圈壳幔韧性剪切带系统   总被引：12，自引：0，他引：12  

蔡学林  曹家敏  朱介寿  程先琼 《地学前缘》2008,15(3):36-54

众多地震测深剖面的地质构造解析显示,大陆岩石圈存在既有显著差异又有密切联系的两套断裂系统,即以地壳表层脆性剪切带为主的浅层断裂系统和以切割莫霍界面的壳幔韧性剪切带为主的深部断裂系统。根据地震测深速度结构特征,结合深部构造岩石地球化学的综合研究,将切割莫霍界面或壳幔过渡带的壳幔韧性剪切带划分为三类(俯冲带、缝合带和剪切带)五型(大陆岩石圈边缘海沟俯冲带、大陆岩石圈碰撞缝合带、挤压型壳幔韧性剪切带、伸展型壳幔韧性剪切带和走滑型壳幔韧性剪切带)。建立起中国大陆岩石圈构造变形由地壳表层向深部扩展以及由壳幔过渡带向地壳中上部扩展的岩石圈双向扩展模式。壳幔韧性剪切带既是无机成因天然气等深部流体的通道,又是地震活动区的发震构造之一,因此研究大陆岩石圈壳幔韧性剪切带具有重要学术价值和实际意义。  相似文献   

南海北部海陆过渡带地壳结构的研究现状及展望   总被引：2，自引：0，他引：2  

夏少红  赵明辉  丘学林 《华南地震》2008,28(4):9-17

首先总结了前人在南海北部海陆过渡带获得的研究成果：由重磁异常、水深及卫星影像等资料推测滨海断裂带存在于南海北部海陆过渡地区：介绍了最近在南海北部海陆过渡地区开展的海陆地震联测试验,其结果显示有一个穿透整个地壳的低速破碎带发育于海陆过渡地区,推测它为滨海断裂带在速度上的表现,另外广泛分布于华南大陆的中地壳低速层在海陆过渡处也有较好发育;总结了天然地震层析成像在南海北部海陆过渡带的研究成果。最后结合目前的研究现状,指出了今后我们的研究方向：在逐步完善目前海陆地震联测试验的基础上,同时开展海陆过渡带的多道地震数据采集及地球化学研究：加强海陆过渡带的地震监测。进行震源机制解和人工地震与天然地震联合成像的研究。  相似文献   

南海中北部地壳深部结构探测新进展   总被引：7，自引：0，他引：7  

吴振利  阮爱国  李家彪  丁巍伟  李湘云  丘学林  赵明辉  郭兴伟 《华南地震》2008,28(1):21-28

2006年8～10月间．国家海洋局第二海洋研究所使用德国SEDIS型三分量海底地震仪以气枪为震源在南海中北部开展了广角地震反射／折射勘测．这是我国大陆科研单位第一次自主开展长距离多剖面的海底地震仪人工地震探测。勘测线共三条。总长达1176．8km．工区最大水深4137m．共投放48台次,回收成功率95-8％。所获得的数据质量良好,深部信息丰富．可直观地分辨出照、Pn、PmP等震相,为南海中北部深部地壳结构、洋壳与陆壳分界和西北、西南次海盆的形成演化研究提供了重要的依据。  相似文献   

利用远震接收函数研究湖北地区地壳结构     

何凯  杜瑞林  董彦君  魏贵春  申学林  戴苗 《大地测量与地球动力学》2018,38(6):646-649

利用2014~2015年湖北数字地震台网30个子台记录的远震波形资料，用频率域反褶积方法提取接收函数，由H-Kappa、CCP叠加方法反演得到各台站下方地壳厚度、泊松比及剖面AA′。结果表明：1）湖北地区地壳厚度总体趋势是西厚东薄，鄂西北、西南地区地壳厚度在45~55 km左右，鄂东地区地壳厚度在30~35 km左右；2）湖北地区泊松比值总体变化不大（0.23~0.27），说明这一地区岩石可能以中度组分为主；3）AA′剖面中出现“楼梯状”Moho面，结合相关文献分析，在武当山地区下方地壳的榴辉岩发生相变，使得相变后的下地壳密度改变而发生拆沉作用，因此鄂西地区地壳厚度发生陡变。  相似文献   

南海东部海沟的震源机制解及其构造意义   总被引：4，自引：0，他引：4       下载免费PDF全文

朱俊江  丘学林  詹文欢  徐辉龙  孙龙涛 《地震学报》2005,27(3):260-268

摘要 根据马尼拉海沟及邻区地震、 火山活动的分析, 并结合地震震源机制和地球物理资料分析, 发现马尼拉海沟在深度200多公里仍为俯冲的性质, 深地震主要集中在12deg;N~14deg;N之间, 地震密集区出现明显的分段特征, 从北到南深度逐渐变深. 震源机制解所反映的最大主压应力轴（P轴）以菲律宾大断层为界, 北部主要为NW向; 南部较为复杂, 为NW, NE和近NS向. 显示了北部以挤压逆冲为特征, 南部以顺时针旋转为特征. 菲律宾板块向西仰冲所产生的构造应力, 被马尼拉海沟的斜向俯冲, 菲律宾大断层的左旋走滑, 以及民都洛断层的左旋走滑所调节.   相似文献   

Seismic structure in the northeastern South China Sea: S-wave velocity and Vp/Vs ratios derived from three-component OBS data     

Minghui Zhao  Xuelin Qiu  Shaohong Xia  Huilong Xu  Ping Wang  Tan K. Wang  Chao-Shing Lee  Kanyuan Xia 《Tectonophysics》2010,480(1-4):183-197

A nearly 500-km-long seismic profile with reflective and refractive wide-angle Ocean Bottom Seismometer (OBS) data and Multi-Channel Seismic (MCS) data was acquired across the northeastern continental margin of the South China Sea (SCS). The S-wave crustal structure and Vp/Vs ratios have been obtained based on a previously published P-wave model using the software RayInvr. Modeling of vertical- and horizontal-component OBS data yields information on the seismic crustal velocities, lithology, and geophysical properties along the OBS-2001 seismic profile. S-wave velocities in the model increase generally with depth but exhibit high spatial variability, particularly from the shelf to the upper slope of the northeastern SCS margin. Vp/Vs ratios also reveal significant lithological heterogeneity. Dongsha–Penghu Uplift (DPU) is a tectonic zone with a thicker crust than adjacent areas and a high magnetic anomaly. With a Vp/Vs of 1.74 and a P-wave velocity of 5.0–5.5 km/s, the DPU primarily consists of felsic volcanic rocks in the upper crust and is similar to the petrology of Zhejiang–Fujian volcanic provinces, which perhaps is associated with a Mesozoic volcanic arc. The ocean–continent transition (OCT) in the northeastern SCS is characterized by a thinning continental crust, volcanoes in the upper crust, and a high velocity layer (HVL) in the lower crust. The S-wave velocity and Vp/Vs ratio suggest that the HVL has a mafic composition that may originate from underplating of the igneous rocks beneath the passive rifted crust after the cessation of seafloor spreading.  相似文献   

粤西沿海震动图的生成和研究     

熊厚  叶春明  黄文辉  丘学林  卫小冬 《华南地震》2011,31(4):85-97

震动图是描绘地震产生的地面运动和可能破坏情况的有效工具,主要包括峰值地面速度(PGV)等值线图、峰值地面加速度(PGA)等值线图和仪器烈度分布图等.基于华南数字地震台网记录到的2010年7月9日MS3.7级阳江地震的数据资料,利用SAC和GMT软件从记录到的地震波形数据提取地面运动参数,生成了PGV和PGA等值线图,并...  相似文献